1/(1*3)+1/(2*4)+1/(3*5)+1/(4*6)……+1/(18*20)
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1/(1*3)+1/(2*4)+1/(3*5)+1/(4*6)……+1/(18*20)
分数形式的说.所有分子都是1 .分母是一个式子.
如果思路好有重赏.
分数形式的说.所有分子都是1 .分母是一个式子.
如果思路好有重赏.
![1/(1*3)+1/(2*4)+1/(3*5)+1/(4*6)……+1/(18*20)](/uploads/image/z/8515092-12-2.jpg?t=1%2F%EF%BC%881%2A3%EF%BC%89%2B1%2F%EF%BC%882%2A4%EF%BC%89%2B1%2F%EF%BC%883%2A5%EF%BC%89%2B1%2F%EF%BC%884%2A6%EF%BC%89%E2%80%A6%E2%80%A6%2B1%2F%EF%BC%8818%2A20%EF%BC%89)
1/(1*3)+1/(2*4)+1/(3*5)+1/(4*6)……+1/(18*20)
各单元的通式为1/[n(n+2)],1/[n(n+2)]=1/2[1/n-1/(n+2)],各单元相加就是1/2[(1/1-1/3)+(1/2-1/4)+(1/3-1/5)+(1/4-1/6)+……+(1/16-1/18)+(1/17-1/19)+(1/18-1/20)]=1/2[1/1+1/2-1/19-1/20]=531/760;不知这样能不能看懂,要能在word上表示就清楚多了.
各单元的通式为1/[n(n+2)],1/[n(n+2)]=1/2[1/n-1/(n+2)],各单元相加就是1/2[(1/1-1/3)+(1/2-1/4)+(1/3-1/5)+(1/4-1/6)+……+(1/16-1/18)+(1/17-1/19)+(1/18-1/20)]=1/2[1/1+1/2-1/19-1/20]=531/760;不知这样能不能看懂,要能在word上表示就清楚多了.
1/(1*3)+1/(2*4)+1/(3*5)+1/(4*6)……+1/(18*20)
(1-1/2)*(1-1/3)*(1-1/4)*(1-1/5)*(1-1/6)*…*(1-1/19)*(1-1/20)=
1.动脑筋计算:(1+1/2)*(1+1/4)*(1+1/6)*…* (1+1/10)*(1-1/3)*(1-1/5)*
计算1+(-2)+3+(-4)+5+(-6)+…+19+(-20)得( )
简算1/(2×3)+1/(3×4)+1/(4×5)+……+1/(18×19)+1/(19×20)
1+3+5+7+……+19+(-2)+(-4)+(-6)+(-8)+……+(-20)
初一计算题:1÷(1×2×3×4)+1÷(2×3×4×5)+1÷(3×4×5×6)+……+1÷(17×18×19×20)
计算:(1-1/2)(1/3-1)(1-1/4)(1/5-1)……(1-1/2010)(1/2011-1)
(1-1/2)(1/3-1)(1-1/4)(1/5-1)……(1/2003-1)(1-1/2004)
(1-1/2+1/3-1/4+……+1/19-1/20)/[1/(11×20)+1/(12×19)+……+1/(15×1
(1-1/2)×(1-1/3)×(1-1/4)×(1-1/5)×(1-1/6)×…×(1-1/19)×(1-1/20)=
(1-1/2)*(1-1/3)*(1-1/4)…(1-1/20),简便算法